[google-sheets] QUERY syntax using cell reference

I know this is an old thread but I had the same question as the OP and found the answer:

You are nearly there, the way you can include cell references in query language is to wrap the entire thing in speech marks. Because the whole query is written in speech marks you will need to alternate between ' and " as shown below.

What you would need is this:

=QUERY(Responses!B1:I, "Select B where G contains '"& B1 &"' ")

If you then wanted to refer to multiple cells you could add more like this

=QUERY(Responses!B1:I, "Select B where G contains '"& B1 &"' and G contains '"& B2 &"' ")

The above would filter down your results further based on the contents of B1 and B2.